Not applicable.
The present invention generally relates to a process for inhibiting gel formation of laundry detergent tablets containing anionic and/or nonionic surfactants, and particularly ethoxylated nonionic surfactants upon their introduction into water. More particularly, highly concentrated anionic and nonionic surfactants, and especially ethoxylated nonionic surfactants, when dispersed in water, tend to form highly viscous gels. Gel formation is immediate, particularly when linear alcohol ethoxylates having a high ethylene oxide content are hydrated.
This gel formation can significantly inhibit the complete hydration and dispersion of an anionic and/or nonionic surfactant, and particularly an ethoxylated nonionic surfactant, in solution. Since detergents used for various types of cleaning processes, such as the laundering of clothes, require rapid dispersion of the surfactant in water in order to realize optimal cleaning effect, it is imperative that an effective solution to this gelling phenomenon be found.
Reducing the gelling tendency of anionic and nonionic surfactants, especially nonionic ethoxylates such as LAE and NPE present in detergent compositions, is important for various cleaning product applications. In heavy duty laundry powders and liquids, surfactant gelling slows down the dissolution rate of the detergent composition, resulting in poor cleaning performance and residues.
This problem is particularly acute with respect to laundry detergents in tablet form. Two types of laundry detergent tablet formulations are becoming popular with consumers, namely, detergent tablets in solid form and those which contain a concentrated liquid inside a soluble outer shell/covering made, for example, from a cellulosic material. The popularity of these types of laundry detergent tablet formulations is already growing quickly in Europe, and similar products are currently being introduced in the US and throughout the world. However, due to the high concentration of anionic and/or nonionic surfactants present in these tablet formulations, surfactant gelling caused by hydration of these surfactants upon exposure to water inhibits1) in the case of solid tablets, the direct contact of the water with the disintegration agents contained in the solid tablet formulations used to facilitate the swelling and break up of the tablet for rapid dissolution, 2) in the case of liquid tablets, the rapid and complete dispersion of the product formulation in the wash liquor. In either case, the tablet dissolution can be incomplete resulting in poor product performance and unwanted residues in the wash tub and on the consumer""s laundry.
In the case of solid tablets, these surfactants, especially nonionic ethoxylates, when hydrated will gel and encapsulate the disintegration agents. These disintegration agents (e.g. swelling cellulosic polymers), however, require contact with water in order to expand/swell. Therefore it is important to reduce or eliminate the gelling affect of these anionic and/or nonionic surfactants.
As was alluded to above, liquid laundry xe2x80x9cTabletsxe2x80x9d or pouches are the newest laundry detergent products recently launched in Europe. These laundry detergent pouches are based on highly active surfactant systems, typically nonionic based, with minimal water content. Reducing the gelling tendency of these products upon hydration is critical to optimal cleaning.
Finally, with respect to processing aids for aqueous based liquid surfactant products, surfactant gelling which occurs during the processing of liquid products will significantly slow down the process time, thus adding to its costs.
The present invention is directed to a process for inhibiting tablet-form laundry detergents from gelling upon hydration involving the steps of: (a) providing a detergent formulation containing a surfactant selected from the group consisting of an anionic surfactant, a nonionic surfactant, and mixtures thereof; (b) providing an anti-gelling agent selected from the group consisting of an alkyl polyglycoside corresponding to formula I:
R1O(Z)axe2x80x83xe2x80x83(I) 
wherein R1 is a monovalent organic radical having from about 6 to about 30 carbon atoms; Z is a glucose residue; a is a number having a value from about 1 to about 6; a polymeric surfactant comprising at least one product of the reaction between:
(i) at least one linking agent of formula II:
R2(Y)3xe2x80x83xe2x80x83(II) 
wherein each Y group is a halogen atom or one Y group is a halogen atom and two Y groups with two adjacent carbon atoms in the R2 group and an oxygen atom form an epoxy group, and R2 is an alkanetriyl group containing from 3 to 10 carbon atoms; and
(ii) at least one compound of formula (III)
R3(EO)n(PO)m(BO)pXxe2x80x83xe2x80x83(III) 
wherein R3 is a substituted or unsubstituted saturated or unsaturated, aliphatic oxy or thio group having from 1 to about 36 carbon atoms or a secondary amino group having from 2 to about 36 carbon atoms; n, m, and p are independently numbers of from 0 to about 50; X is hydrogen, or a mercapto group or an amino group in place of a terminal xe2x80x94OH group, provided that when X is mercapto or amino, the sum of n, m, and p must be at least 1; and wherein the mole ratio of component (I) to component (ii) is from about 0.2/1 to about 5/1; an alkyl sulfate; and mixtures thereof; (c) combining the detergent formulation and the anti-galling agent to form a finished formulation and; (d) processing the finished formulation into a tablet-form laundry detergent product.
The present invention is also directed to a process for inhibiting an ethoxylated nonionic surfactant present in a cleaning composition from gelling upon hydration, the process involving:
(a) providing an ethoxylated nonionic surfactant;
(b) providing an anti-gelling agent selected from the group consisting of an alkyl polyglycoside corresponding to formula I:
R1O(Z)axe2x80x83xe2x80x83(I) 
wherein R1 is a monovalent organic radical having from about 6 to about 30 carbon atoms; Z is a glucose residue; a is a number having a value from about 1 to about 6; a polymeric surfactant comprising at least one product of the reaction between:
(i) at least one linking agent of formula II:
R2(Y)3xe2x80x83xe2x80x83(II) 
wherein each Y group is a halogen atom or one Y group is a halogen atom and two Y groups with two adjacent carbon atoms in the R2 group and an oxygen atom form an epoxy group, and R2 is an alkanetriyl group containing from 3 to 10 carbon atoms; and
(ii) at least one compound of formula (III)
R3(EO)n(PO)m(BO)pXxe2x80x83xe2x80x83(III) 
wherein R3 is a substituted or unsubstituted saturated or unsaturated, aliphatic oxy or thio group having from 1 to about 36 carbon atoms or a secondary amino group having from 2 to about 36 carbon atoms; n, m, and p are independently numbers of from 0 to about 50; X is hydrogen, or a mercapto group or an amino group in place of a terminal xe2x80x94OH group, provided that when X is mercapto or amino, the sum of n, m, and p must be at least 1; and wherein the mole ratio of component (i) to component (ii) is from about 0.2/1 to about 5/1; an alkyl sulfate; and mixtures thereof; and
(c) mixing the ethoxylated nonionic surfactant with the anti-gelling agent.
Not applicable.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions are to be understood as being modified in all instances by the term xe2x80x9caboutxe2x80x9d.
The term xe2x80x9ctablet-formxe2x80x9d is meant to encompass concentrated laundry detergents in the form of solid tablets, concentrated liquid detergent formulations present inside a water-soluble outer covering, i.e., a pouch, and the like.
The present invention is directed to the surprising discovery that the gelling tendencies of concentrated anionic and/or nonionic surfactants, and particularly ethoxylated nonionic surfactants, when placed in water, can be significantly reduced by blending the surfactant(s) with the anti-gelling agent of the present invention.
Any type of anionic and/or nonionic surfactants, typically employed in detergent formulations, may be employed in the process of the present invention. However, particularly preferred surfactants are the nonionic ethoxylates. Examples thereof include, but are not limited to, linear alcohol ethoxylates having from about 8 to about 20 carbon atoms, preferably from about 10 to about 18 carbon atoms, and most preferably from about 12 to about 16 carbon atoms and from about 1 to about 20 moles of ethylene oxide, preferably from about 4 to about 16 moles of ethylene oxide, and most preferably from about 6 to about 12 moles of ethylene oxide, and nonyl-phenol ethoxylates having from about 1 to about 20 moles of ethylene oxide, preferably from about 4 to about 16 moles of ethylene oxide and most preferably from about 6 to about 12 moles of ethylene oxide, oxo-linear alcohols having from about 8 to about 20 carbon atoms, preferably from about 12 to about 15 carbon atoms, and from about 1 to about 20 moles of ethylene oxide, preferably from about 6 to about 12 moles of ethylene oxide, natural linear alcohols having from about 8 to about 20 carbon atoms, preferably from about 12 to about 16 carbon atoms, and from about 1 to about 20 moles of ethylene oxide, preferably from about 6 to about 12 moles of ethylene oxide.
Particularly preferred ethoxylated nonionic surfactants for use in the process of the present invention include a C12-15 linear alcohol having 7 moles of ethylene oxide.
One of the anti-gelling agents for use in the present invention is an alkyl polyglycoside corresponding to formula I:
R1O(Z)axe2x80x83xe2x80x83I 
wherein R1 is a monovalent organic radical having from about 6 to about 30 carbon atoms; R2 is a divalent alkylene radical having from 2 to 4 carbon atoms; Z is a saccharide residue having 5 or 6 carbon atoms; b is a number having a value from 0 to about 12; a is a number having a value from 1 to about 6. Preferred alkyl polyglycosides which can be used in the compositions according to the invention have the formula I wherein Z is a glucose residue and b is zero. Such alkyl polyglycosides are commercially available, for example, as APG(copyright), GLUCOPON(copyright), or PLANTAREN(copyright) surfactants from Cognis Corporation, Ambler, Pa., 19002.
Examples of such surfactants include but are not limited to:
1. GLUCOPON(copyright) 225 Surfactantxe2x80x94an alkyl polyglycoside in which the alkyl group contains 8 to 10 carbon atoms and having an average degree of polymerization of 1.7.
2. GLUCOPON(copyright) 425 Surfactantxe2x80x94an alkyl polyglycoside in which the alkyl group contains 8 to 16 carbon atoms and having an average degree of polymerization of 1.5.
3. GLUCOPON (copyright) 625 Surfactantxe2x80x94an alkyl polyglycoside in which the alkyl group contains 12 to 16 carbon atoms and having an average degree of polymerization of 1.6.
4. APG(copyright) 325 Surfactantxe2x80x94an alkyl polyglycoside in which the alkyl group contains 9 to 11 carbon atoms and having an average degree of polymerization of 1.5.
5. GLUCOPON(copyright) 600 Surfactantxe2x80x94an alkyl polyglycoside in which the alkyl group contains 12 to 16 carbon atoms and having an average degree of polymerization of 1.4.
6. PLANTAREN(copyright) 2000 Surfactantxe2x80x94a C8-16 alkyl polyglycoside in which the alkyl group contains 8 to 16 carbon atoms and having an average degree of polymerization of 1.5.
7. PLANTAREN(copyright) 1300 Surfactantxe2x80x94a C12-16 alkyl polyglycoside in which the alkyl group contains 12 to 16 carbon atoms and having an average degree of polymerization of 1.6.
8. GLUCOPON(copyright) 220 Surfactantxe2x80x94an alkyl polyglycoside in which the alkyl group contains 8 to 10 carbon atoms and having an average degree of polymerization of 1.5.
Other examples include alkyl polyglycoside surfactant compositions which are comprised of mixtures of compounds of formula I wherein Z represents a moiety derived from a reducing saccharide containing 5 or 6 carbon atoms; a is a number having a value from 1 to about 6 preferably from 1.4 to 1.7; b is zero; and R1 is an alkyl radical having from 8 to 20 carbon atoms, preferably from 8 to 16 carbon atoms. The compositions are characterized in that they have increased surfactant properties and an HLB (hydrophile-lipophile balance) in the range of about 10 to about 16 and a non-Flory distribution of glycosides, which is comprised of a mixture of an alkyl monoglycoside and a mixture of alkyl polyglycosides having varying degrees of polymerization of 2 and higher in progressively decreasing amounts, in which the amount by weight of polyglycoside having a degree of polymerization of 2, or mixtures thereof with the polyglycoside having a degree of polymerization of 3, predominate in relation to the amount of monoglycoside, said composition having an average degree of polymerization of about 1.8 to about 3. Such compositions, also known as peaked alkyl polyglycosides, can be prepared by separation of the monoglycoside from the original reaction mixture of alkyl monoglycoside and alkyl polyglycosides after removal of the alcohol. This separation may be carried out by molecular distillation and normally results in the removal of about 70-95% by weight of the alkyl monoglycosides. After removal of the alkyl monoglycosides, the relative distribution of the various components, mono- and poly-glycosides, in the resulting product changes and the concentration in the product of the polyglycosides relative to the monoglycoside increases as well as the concentration of individual polyglycosides to the total, i.e., DP2 and DP3 fractions in relation to the sum of all DP fractions. Such compositions are disclosed in U.S. Pat. No. 5,266,690, the entire contents of which are incorporated herein by reference.
A particularly preferred alkyl polyglycoside for use in the present invention is one wherein in formula I R1 is a monovalent organic radical having from about 8 to about 16 carbon atoms, and preferably from about 8 to about 11 carbon atoms, and a is a number having a value of from about 1.3 to about 1.6, and preferably about 1.5. It should be noted, however, that other types of nonionic sugar surfactants such as ethoxylated alkyl polyglycosides, glucamides, and the like might also be used without departing from the spirit of the invention.
Another anti-gelling agent used in the process of the present invention is a polymeric surfactant comprising at least one reaction product of the reaction between:
(i) at least one linking agent of formula II:
R2(Y)3xe2x80x83xe2x80x83(II) 
wherein each Y group is a halogen atom or one Y group is a halogen atom and two Y groups with two adjacent carbon atoms In the R2 group and an oxygen atom form an epoxy group, and R2 is an alkanetriyl group containing from 3 to 10 carbon atoms; and
(ii) at least one compound of formula (III)
R3(EO)n(PO)m(BO)pXxe2x80x83xe2x80x83(III) 
wherein R3 is a substituted or unsubstituted saturated or unsaturated, aliphatic oxy or thio group having from 1 to about 36 carbon atoms or a secondary amino group having from 2 to about 36 carbon atoms; n, m, and p are independently numbers of from 0 to about 50; X is hydrogen, or a mercapto group or an amino group in place of a terminal xe2x80x94OH group, provided that when X is mercapto or amino, the sum of n, m, and p must be at least 1; and wherein the mole ratio of component (i) to component (ii) is from about 0.2/1 to about 5/1.
The linking agent of formula (II) is preferably epichlorohydrin although other epihalohydrins can be used. Also, trihaloalkanes can be used, such as 1,2,3-trichloropropane, 1,2,4-trichlorobutane, 1,3,6-trichlorohexane and the like. Instead of chlorine in the epihalohydrins and the trihaloalkanes, the corresponding bromine and iodine compounds can also be used, including compounds containing two or even three of the above halogens.
In regard to formula III, the nonoxy and nonthio components of the R3 aliphatic group can be any substituted or unsubstituted, saturated or unsaturated aliphatic moiety having from 1 to 36 carbon atoms. Thus, the nonthio and the nonoxy components of the R3 aliphatic group can be linear or branched alkyl groups, linear or branched alkenyl or alkynyl groups, saturated carbocyclic moieties, unsaturated carbocyclic moieties having one or more multiple bonds, saturated heterocyclic moieties, unsaturated heterocyclic moieties having one or more multiple bonds, substituted linear or branched alkyl groups, substituted linear or branched alkenyl or alkynyl groups, substituted saturated carbocyclic moieties, substituted unsaturated carbocyclic moieties having one or more multiple bonds, substituted saturated heterocyclic moieties, and substituted unsaturated heterocyclic moieties having one or more multiple bonds. Examples of the above include but are not limited to an alkyl group having from 4 to 22 carbon atoms, an alkenyl group having from 4 to 22 carbon atoms, and an alkynyl group having from 4 to 22 carbon atoms. R3 can also be an arenyl group. Arenyl groups are alkyl-substituted aromatic radicals having a free valence at an alkyl carbon atom such as a benzylic group. Alkyl groups having from 4 to 12 carbon atoms are preferred, and alkyl groups having from 8 to 10 carbon atoms are most preferred. The degree of ethoxylation is preferably from 2 to about 50 with the most preferred being from about 4 to about 50 while the degree of propoxylation and butoxylation can vary from 0 to about 50, preferably from 1 to about 10. The degree of propoxylation and or butoxylation will be determined by the desired degree of water solubility or miscibility. The water solubility or miscibility will ultimately be determined by such factors as the number of carbon atoms in R3, the relative amounts EO, PO and BO and the effect of PO and BO on the biodegradability of the final composition.
When the X group of formula (III) is a mercapto group, the R3 group will preferably have from about 4 to about 36 carbon atoms, n is from 0 to about 50, m is from 0 to about 50 and p is from 0 to about 50, examples of which include but are not limited to, alkoxylated dodecyl mercaptan and alkoxylated 1-hexadecanethiol.
The compounds of formula (III) can be alkoxylated or non-alkoxylated secondary amines. When the compounds of formula II are secondary amines, n is a number from 0 to 50, preferably from 1 to 50, m is a number from 0 to 50 and p is a number form 0 to 50, preferably from 1 to 50. Examples of the secondary amines useful for the purposes of the invention include but are not limited to, alkoxylated dibutyl amine, alkoxylated dicyclohexyl amine, alkoxylated diethylethanolamine, and alkoxylated dioctylamine.
Optionally an additional component can be reacted with the linking agent of formula (II) and the compound of formula (III). A glycidyl ether or amine can be added to the reaction of formula (II) and formula (III). The amount of the glycidyl ether or glycidyl amine is from about 1 to about 20 mole percent based on the moles of Formula (III) used in the reaction. When the glycidyl ether or glycidyl amine is added to the monofunctional starting material of formula III the ratio of formula II to Formula III plus the glycidyl ether or glycidyl amine is preferably from about 0.8 to about 1.4. Examples of the glycidyl ethers include, but are not limited to, PEG 600 Diglycidyl ether, TETRONIC(trademark) 701 Tetraglycidyl ether, Triglycidyl Di or Triethanolamine, Polyoxyethylene (POE) 200 Tallow amine diglycidyl ether, Propoxylated (POP10) Trimethylol propane triglycidyl ether, Propoxylated (POP7) Pentaerythritol tetraglycidyl ether. Examples of Glycidyl amines include but are not limited to, Tetraglycidyl 1,6-Hexane diamine, Tetraglycidyl JEFFAMINE(trademark) EDR-148, and Tetraglycidyl Isophorone diamine.
A particularly preferred polymeric surfactant for use in the present invention is the reaction product of a C8-10 fatty alcohol having about 4.5 moles of ethylene oxide and epichlorohydrin commercially available from Cognis Corporation, Ambler Pa. under the name DEHYPOUND(trademark) ST-15.
Alkyl sulfates may also be used as anti-gelling agents in order to inhibit the gelling of ethoxylated nonionic surfactants upon hydration. Examples of suitable alkyl sulfates include, but are not limited to, those having from about 8 to about 10 carbon atoms. A particularly preferred alkyl sulfate for use in the process of the present invention is octyl sulfate. In the event that an alkyl sulfate is used, it will typically be employed in a ratio by weight of ethoxylated nonionic surfactant to alkyl sulfate ranging from about 20:1 to about 1:1; from about 15:1 to about 1:1; from about 10:1 to about 1:1; and from about 5:1 to about 1:1.
According to one embodiment of the present invention there is provided a process for inhibiting anionic and/or nonionic surfactants, present in tablet-form laundry detergents. from gelling upon hydration, involving the steps of: (a) providing a detergent formulation containing a surfactant selected from the group consisting of an anionic surfactant, a nonionic surfactant, and mixtures thereof; (b) providing an anti-gelling agent selected from the group consisting of an alkyl polyglycoside corresponding to formula I:
R1O(Z)axe2x80x83xe2x80x83(I) 
wherein R1 is a monovalent organic radical having from about 6 to about 30 carbon atoms; Z is a glucose residue; a is a number having a value from about 1 to about 6; a polymeric surfactant comprising at least one product of the reaction between:
(i) at least one linking agent of formula II:
R2(Y)3xe2x80x83xe2x80x83(II) 
wherein each Y group is a halogen atom or one Y group is a halogen atom and two Y groups with two adjacent carbon atoms in the R2 group and an oxygen atom form an epoxy group, and R2 is an alkanetriyl group containing from 3 to 10 carbon atoms; and
(ii) at least one compound of formula (III)
R3(EO)n(PO)m(BO)pXxe2x80x83xe2x80x83(III) 
wherein R3 is a substituted or unsubstituted saturated or unsaturated, aliphatic oxy or thio group having from 1 to about 36 carbon atoms or a secondary amino group having from 2 to about 36 carbon atoms; n, m, and p are independently numbers of from 0 to about 50; X is hydrogen, or a mercapto group or an amino group in place of a terminal xe2x80x94OH group, provided that when X is mercapto or amino, the sum of n, m, and p must be at least 1; and wherein the mole ratio of component (i) to component (ii) is from about 0.2/1 to about 5/1; an alkyl sulfate; and mixtures thereof; (c) combining the detergent formulation and the anti-gelling agent to form a finished formulation and; (d) processing the finished formulation into a tablet-form laundry detergent product.
In the event that the anti-gelling agent selected is an alkyl polyglycoside, it will be mixed with the ethoxylated nonionic surfactant in a ratio by weight of ethoxylated nonionic surfactant to alkyl polyglycoside ranging from about 20:1 to about 1:1; from about 15:1 to about 1:1; from about 10:1 to about 1:1; and from about 5:1 to about 1:1.
Similarly, if the anti-gelling agent selected is the polymeric surfactant, it will be mixed with the ethoxylated nonionic surfactant in a ratio by weight of ethoxylated nonionic surfactant to polymeric surfactant ranging from about 50:1 to about 1:1; from about 20:1 to about 1:1; from about 10:1 to about 1:1; and from about 5:1 to about 1:1.
In the event that a mixture of alkyl polyglycoside and polymeric surfactant is employed, the ratio by weight of ethoxylated nonionic surfactant to anti-gelling agent mixture will range from about 20:1 to about 1:1; from about 15:1 to about 1:1; from about 10:1 to about 1:1; and from about 5:1 to about 1:1.
The present invention will be better understood from the examples which follow, all of which are intended for illustrative purposes only and are not meant to unduly limit the scope of the invention in any way.